Electric acoustic receiver



Sept 20, 1938. E. L, BowLEs 2,130,414

ELECTRIC vACOUSTIC RECEIVER Filed 4 Oct 7, 1932 Rec VER 1'7"? venia? AMP FIEE wo 142153I unirse stares 3:;1;

Patented Sept. 20, 1938 ELECTRIC ACOUSTKC RECEIVER Edward Lindley Bowles, Wellesley Farms, Mass.

Application October 7, 1932, Serial No. 636,705

3 Claims. (Cl. 177-352) UNAM The present invention relates to signaling, and more particularly to electric-acoustic receivers.

The speed of travel of electric waves, such as radio Waves, in free space, asis well known, is that of light which', in the case of many problems, may be considered as substantially instantaneous. The velocity of sound in air, on the other hand, as is also well known, is very low-,by comparison,

. being, under normal conditions of sound intensity and atmosphere, in the neighborhood of 1,000 ft. per second, and in water only about four times this latter value.

An object of the present invention, therefore, is to provide a novel electric-acoustic receiver for indicating or otherwise determining this difference in the speeds of travel of electric waves and of audible or super-audible sound waves in either air or water to determine either the position or the direction, or both, of one object with respect to another.

It is well known, forexample, that if a ship at the transmitting station, is equipped to send out radio waves modulated by a 1,000 cycle (or any other value) oscillator, for very short periods; and if., at the same time, a signal in the form of an acoustic wave is sent out from this same modulating source, and for short periods of the same duration; then another vessel, at the receiving station, equipped to receive both the periodically modulated radio signal and the periodic sound signal, will` in accordance with the present invention, and by Virtue of thediierence in time of arrival of these two modulating impulses, be able to determine the distance or the direction, or both, of the transmitting ship. v

If the difference in time between the arrival of the sound wave, through the air. let us say, and the modulation pulse in the radio wave is one second, the distance of the transmitting boat, or lother object, from the receiving source, will be 1,000 feet. If the difference is two seconds, the

corresponding distance is 2.000 feet; if three seconds, 3,000 feet; and so on. The time interval between the arrival of a pulse of the modulated radio wave and the arrival of the acoustic Wave pulse is thus a measure of the distance between the transmitting and the receiving stations.

If the sound-radiating device is coupled to the water rather than to the air of a transmitting medium, and if, all other conditions remaining the same, the difference of arrival of the two 'pulses is one second, the distance between stations would be approximately 4,000 feet.

As an example of elastic waves, reference might be made to acoustic or sound Waves, whether audiadapted for use in the said receiver.

Other and further objects will be explained hereinafter, and will be particularly pointed out in the appended claims.

The invention will now be explained more fully in connection with the accompanying drawing, the single figure of which is a diagrammatic view of circuits and apparatus arranged and constructed according to a preferred embodiment of the present invention, illustrating a. receiver of electric and acoustic waves together with a time interval measuring or indicating device.

A radio receiver 2l of any convenient type is diagrammatically shown associated with a conventional loop antenna 23 and a vertical antenna 25 to render it unidirectionally responsive. The loop 23 has a fixed axis 33, to which is fixed also a directional sound receiver 2t, comprising, preferably, a parabolic reflector or concentrator 2l and a microphone 28 disposed at the focus of the reflector 21. In this way, the radio-wave and the soundwave receivers 23 and 26 are oriented in like manner, both pointing to the same source of the respective waves. The microphone 2S is connected, by conductors 22, to an amplier 29 which, in turn, is connected by conductors 2li, to a relay ll. A direct indication of the distance between the sending and the receiving vessels, or other objects, may be furnished oy the indicating device |00 comprising an indicating needle 10 and an associated scale 1l.

A control tube 18 of the grid controlled are type for example is employed. This is a gaseous tube, so arranged and adjusted that. if the bias voltage on its grid 95 is kept suiiiciently negative, there will be no arc conduction between its thermionic lament 91 and its plate or anode 9-9. Under these conditions, the grid 95 will exercise a control of the thermionic space current from the cathode 91 to the anode 99. just as in any other threeelectrode, high, vacuum tube. If. on the other hand, the voltage of the grid 95 is gra dually made more and more positive, a point will be reached when an arc discharge will take place between the thermionic cathode 91 and the anode 99. After this arc takes place, the grid 95 loses all control ot the space current from thellament 91 to the plate 99. The control of the grid can be restored by interrupting the plate circuit, and by making ie grid again negative to the proper degree, and

ien reconnecting the anode circuit.

The needle 10 is fixed to a shaft |0|, to which i fixed a small disc |03 of magnetic material. nmediately above this disc is a magnetic driving oil 13 which, when excited, magnetizes a rotatble plate |05, causing it to attract the disc |03 nd thereby to clutch this disc and connect it lgidly to the element |05. A thin iilm 68 of noniagnetic material is placed between the magnetic lement and the disc |03, so that they shall .ot tend to adhere due to any slight remanent magnetic effect. The current is led into and out f this clutch-control coil 13, along conductors 39 `nd 40, by means of commutators |01and |08, counted upon an insulating cylinder H4, and .ssociated with brushes and ||3. The comnutators |01 and |08, the cylinder H4, the conluctors 39 and 40 mounted therein, and the clutch ontrol coil 13 are rigidly xed with respect to ne another thereby forming a unitary structure. The cylinder ||4 carries also a gear ||1 operated )y a pinion I9- that is driven from a synchronous notor 8| through a pinion |20 and a gear |2|. ['he synchronous motor 8| is driven at a prede- ;ermined speed by means of a vacuum-tube oscilator or other power source 83.

When the circuit of the coil 13 is open, land the :lutch |03, |05 is, therefore, ineiective, the syn- :hronous motor 8| rotates the cylinder ||4 and ,ts associated, fixed parts, without turning the disk |03, the needle shaft |0| and the needle 10 mounted thereon. If a current is now sent in through the brush l, and out through its brush ||3, or vice versa, the clutch control coil 13 will magnetize the clutch face |05, thus causing the shaft |0| to turn with the gear ||1. The needle 10with the shaft |0| and the needle structure associated therewith, will continue to rotate, the needle 10, progressing along the scale 1|, just as long as there is current in the clutch coil 13. To

prevent the needle from moving 01T the scale 1|, a

protective relay |23 is arranged to short-circuit the clutch coil 13 at points |25 and |26 and is actuated by the pressure of the needle 10 as it reaches the upper end of its scale range.

The needle 10 may at any time be brought back to the zero position, as long as the synchronous motor 8| is in operation, by closingcontact members |21, causing current from a battery |29 to course through a second clutch coil |3I, through brushes |33 and |34. One of the contact members |21 is mounted upon a sliding rod 31, so as to be manipulated by an operating switch handle 19, and the other contact member |21 is stationary. The circuit is from one terminal of the battery |29, by way of a conductor 66, through the contact members |21, by way of a conductor 42, to the brush |33, a commutator |31. by way of a conductor 69. to the coil |3|; and from the coil |3I, by way of a conductor 12, to a commutator |39, the brush |34, and by way of a conductor 61, back to the other terminal of the battery |29. Upon the closing of this circuit, to send current through this clutch coil |3I, a magnetic eld will be created. The entire, lower, magnetic-clutch structure, carrying the coil |3|, the commutators |31 and |39 disposed about an insulating lcylinder .46, and a gear I4 also carried by the cylinder 46,

will thereupon be actuated to rotate the needle 10 in a counter-clockwise direction. This is effected by the synchronous motor 8| driving a pinion |42 that meshes with the gear |4|, the pinion |42 being driven from the pinion by a pinion 41 and a gear 48. The lower clutch is similar to the -brush |f|3, then, past the terminal upper clutch, the clutch disc |03, that is connected rigidly with the needle structure being adapted to become clutched to a lower clutch disc |43. The space between the clutch discs |03 and |43 is made suilciently large so that they do not come in contact. In this way, rotation of the clutch structure will simply bring the needleback to zero, as determined by a stop |41. Further rotation of the lower clutch structure will in no way harm the needle structure because of the above-mentioned space between the elements |03 and |43 and the resulting slip, l

A controlling relay 15 is connected with the radio receiver 2| by the conductors 30 and a controlling relay 11 is similarly connected with the amplifier 29 of the acoustic receiver 26 by the conductors 24. The relay 15 controls normally open or disconnected contact members |6| and the relay 11 controls normally closed or connected contact members |69. The conductors 30 are respectively connected with contact members 81 and 89 and the conductors 24 with contact members 9| and 93. Contact members |5|, |53', |55 and |51 are mounted upon the sliding rod 31, so as to be caused to engage simultaneously the respective contact members 81, 89, 9| and 93.

Assuming that the needle pointer 10 is at zero,

and that the control knob 19 is depressed, the respective pairs-of contact members 81 and |5|, 89 and |53, 9| and |55, and 93 and |51, will become engaged, and the contact members |21 will have become opened, the latter condition precluding th'e existence of any current in the Zero-return clutch coil |3|. Let it further be assumed that a distant ship sends out, simultaneously, an audio pulse, modulating a radio wave, and an audio pulse, acting on the air or water medium directly. The radio pulse, obviously the iirst to arrive. will cause the closing of the contact members |6I of the relay 15. The closing of these contact members |6| will effect the sh'ort-circuiting of a portion of a voltage-divider wire |63, connected between the iilament 91 and the grid 95 ofthe control tube 18. The bias of -the grid 95 will thus become reduced to a point where an arc discharge will take place between the lament 91 and the plate. 99.

The plate current will course from the plate 99, through a limiting resistor |65, past the terminal |25, in through the brush HI, the commutator |08 and the conductor 39, through thellclutc'h control coil 13, conductor 40, commutator |01 and |26 and through a plate battery |61, and through relay contact |69, back to the iilament 91. Owing to the characteristics of the control tube 18 already described, this condition will prevail even after the initiatingrpulse has passed, thus permitting the contact members |6| of relay 15 to reopen. Thus the needle 10 once it has become actuated, will continue to move up the scale 1| until the acoustic pulse received by the acoustic-receiving device 21 causes the contacts |69 of relay 11 to open, thus opening the plate circuit of the control tube 18 and interrupting the l arc. this circuit. the grid 95 is enabled to` regain control of the tube 18 since the contact members |6| of the relay 15 have already opened,v and therefore, the original, higher negative bias already prevails in the tube \18.

If the needle 10 and its moving system have been critically damped by the friction of a threadedly adjusted, 'clamping screw 14, its rotation will cease the moment the current through the clutch AAcoil is` interrupted. The needle 10 will thus come Upon the opening of' the transmitting ship. There will be a definite relationship between this time interval and the distance between the transmitting and the receiving devices. The scale 1| may, therefore, be calibrated to read distance directly.

Modifications within the scope of the present invention will readily occur to persons skilled in the art. It is therefore desired that the abovedescribed embodiment of the invention shall be regarded as illustrative of the invention, and not restrictive, and that the appended claims be construed broadly, except insofar as it may be necessary to impose limitations in view of the prior art.V

What is claimed is:

1. A receiver comprising, means for receiving electric-wave signals, means for receiving acoustic-Wave signals, an indicator, means for actuating the indicator, the said actuating means being normally ineffective, two relays, a grid-controlled, arc tube having input and output circuits respectively controlled by the relays, means controlled by the electric-wave signal receiving means and operative upon the receipt of an electric-wave signal thereby for actuating the input-circuit relay, means controlled by the input circuit upon the actuation of the input-circuit relay for rendering eiective the actuating means to cause the actuating means to start to actuate the indicator and for thereafter maintaining the actuating means effective to actuate the indicator irrespective of the position occupied by the input-circuit relay, means controlled by the acoustic-Wave signal receiving means operative upon the receipt of an acoustic-wave signal thereby for actuating the output-circuit relay, and means controlled by the output-circuit upon the actuation of the outputcircuit relay for rendering the actuating means ineffective, thereby to stop the further actuation of the indicator.

2. A receiver comprising, means for receiving electric-wave signals, means for receiving acoustic-wave signals, an indicator, means for actuating the indicator, the said actuating means being normally ineffective,V a normally open relay, a normally closed relay, a circuit controlled by the normally open relay, a circuit controlled by the normally closed relay, means controlled by the electric-wave signal receiving means for closing the normally open relay, thereby to close the rstnamed circuit, means controlled by the closing of I the rst-named circuit for rendering the actuating means eective to start to actuate the indicator and for thereafter maintaining the actuating means effective to actuate the indicator irrespective .of the position occupied by the normally open relay, means controlled byV the acoustic- Wave signal receiving means for opening the normally closed relay, thereby to open the secondnamed circuit, and means controlled by the opening of the second-named circuit for rendering the 'actuating means ineffective, thereby to stop the further actuation of the indicator.

3. Apparatus for measuring time intervals, comprising a time indicator, means for actuating the indicator, a relay with contact members normally open, a second relay with contact members normally closed, a grid-controlled arc tube having an input circuit in which the normally open contact members are connected to maintain the input circuit normally open and an output circuit in which the normally closed contact members are connected to maintain the output circuit normally closed, means for closing the normally open contact members to close the input circuit, means controlled by the closing of the input circuit to render the actuating means effective to actuate the indicator, means for opening the normally closed contact members to open the output circuit, and means controlled by the opening of the output circuit to render the actuating means ineiective, thereby to stop the further actuation of the indicator.

EDWARD L. BOWLES. 

